U.S. stock index futures extended losses on Friday after a weaker-than-expected July jobs report elevated concerns about the health of the labor market amid uncertainties about U.S. trade policies. A Labor Department report showed the U.S. economy added 73,000 jobs in July, compared with economists' estimate of a rise of 110,000. The unemployment rate stood at 4.2 per cent, in line with expectations, while average earnings rose 0.3 per cent on a monthly basis against a forecast of 0.3 per cent